The primary objective of this proposal is to continue to support and expand Mayo Clinic's participation in the activities of Children's Cancer Group through: 1.) Evaluating new cancer chemotherapeutic agents and developing new approaches to treatment of children with cancer by, a) maintaining a leadership role in CCG Phase II and New Agent Study Committees, b) performing pilot studies for potential incorporation into future randomized CCG trials, c) entering patients on new agent studies, d) utilizing the resources in Doctor Ames' pharmacology laboratory to evaluate the pharmacology and pharmacokinetics of cancer chemotherapy. 2.) Improving treatment and potential for cure of various childhood cancers and leukemias by, a) continuing to enter patients into CCG treatment protocols with the expectation that study entries will increase as new studies for various tumor systems are activated, b) playing a leadership role in CCG Strategy Groups in order to develop new approaches to the treatment of childhood cancer, c) participating in the development of new randomized trials for the treatment of specific diseases and maintaining active participation in CCG study committees by Mayo investigators currently assigned to study committees, d) studying long-term effects of treatment. 3.) Studying the biology and epidemiology of childhood cancer by, a) active participation in regional and CCG case-control epidemiology studies, b) making available to CCG the skills and resources of Mayo investigators in Pathology, Immunology, Molecular Biology, cytogenetics and other areas of basic and applied laboratory research. 4.) Improving supportive care of children with cancer by, a) continued participation in CCG supportive care studies, b) standardization of drug administration procedures for various chemotherapeutic agents, c) development and evaluation of methods for controlling cancer- related and procedure-related side-effects. 5.) Providing access for patients in outlying areas to these clinical research programs through affiliates in Des Moines, Iowa; Fargo, North Dakota; Duluth, Minnesota; Regina and Saskatoon, Sasketchewan; Sioux Falls, South Dakota; and Green Bay, Wisconsin. 6.) Active participation in CCG administrative activities by continuing to chair and participate in appropriate committees, including Membership, Data Monitoring, and Constitution and By-Laws.